Organic light-emitting device and compound

Abstract

An organic light-emitting device including a first electrode, a second electrode facing the first electrode, and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer includes an emission layer, and wherein the emission layer includes a fluorescent compound represented by a specific formula described in the specification.

What is claimed is: 
     
         1 . An organic light-emitting device comprising:
 a first electrode;   a second electrode facing the first electrode; and   an organic layer disposed between the first electrode and the second electrode, wherein the organic layer comprises an emission layer,   wherein   the emission layer comprises a fluorescent compound, of which a difference between a singlet excitation energy level and a triplet excitation energy level is greater than 0 electron volts and equal to or less than 0.5 electron volts,   a proportion of fluorescent emission components with respect to total emission components emitted from the emission layer is about 90% or more, and the emission layer does not include a phosphorescent emission compound,   the fluorescent compound comprises electron donor groups in the number of n1 and electron acceptor groups in the number of n2, wherein n1 and n2 are each independently an integer from 1 to 10,   the electron donor groups in the number of n1 and the electron acceptor groups in the number of n2 are chemically bonded to each other in random order, provided that a chemical bond between the electron donor group and the electron acceptor group is a carbon-carbon single bond,   at least one of the electron donor groups in the number of n1 is an electron donor group represented by Formula 1A, and   the electron acceptor group is selected from groups represented by Formula 1B:   
       
         
           
           
               
               
           
         
         wherein CY 1  and CY 2  in Formula 1A are each independently selected from a benzene group, a naphthalene group, a carbazole group, a fluorene group, a dibenzofuran group, and a dibenzothiophene group, 
         R 1  and R 2  in Formula 1A are each independently selected from: 
         hydrogen, deuterium, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 5 -C 60  carbocyclic group, and a π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group; and 
         a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 5 -C 60  carbocyclic group, and a π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, each substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 5 -C 60  carbocyclic group, a (C 1 -C 10  alkyl)C 5 -C 60  carbocyclic group, a di(C 1 -C 10  alkyl)C 5 -C 60  carbocyclic group, a (phenyl)C 5 -C 60  carbocyclic group, a di(phenyl)C 5 -C 60  carbocyclic group, a (biphenyl)C 5 -C 60  carbocyclic group, a di(biphenyl)C 5 -C 60  carbocyclic group, a π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a (C 1 -C 10  alkyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a di(C 1 -C 10  alkyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a (phenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a di(phenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a (biphenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, and a di(biphenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, 
         b1 and b2 in Formula 1A are each independently an integer from 0 to 6, 
         “*” in Formula 1A indicates a binding site to a neighboring atom, provided that “*” in Formula 1A does not indicate a binding site to an electron acceptor group, 
         CY 1  and CY 2  in Formula 1A are optionally additionally chemically bonded to at least one of an electron donor group and an electron acceptor group, 
         L 11  in Formula 1B is selected from: 
         a single bond, cyclopentane group, a cyclohexane group, a cycloheptane group, a cyclooctane group, a cyclopentene group, a cyclohexene group, a cycloheptene group, a benzene group, a naphthalene group, a fluorene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a pyrrole group, a thiophene group, a furan group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, an isoindole group, an indole group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, a cinnoline group, a phenanthroline group, a benzimidazole group, a benzofuran group, a benzothiophene group, a benzoxazole group, an isobenzoxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a dibenzofuran group, a dibenzothiophene group, a benzocarbazole group, a dibenzocarbazole group, an imidazopyridine group, an imidazopyrimidine group, an azaindole group, an azaindene group, an azabenzofuran group, an azabenzothiophene group, an azacarbazole group, an azafluorene group, an azadibenzofuran group, and an azadibenzothiophene group; and 
         a cyclopentane group, a cyclohexane group, a cycloheptane group, a cyclooctane group, a cyclopentene group, a cyclohexene group, a cycloheptene group, a benzene group, a naphthalene group, a fluorene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a pyrrole group, a thiophene group, a furan group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, an isoindole group, an indole group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, a cinnoline group, a phenanthroline group, a benzimidazole group, a benzofuran group, a benzothiophene group, a benzoxazole group, an isobenzoxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a dibenzofuran group, a dibenzothiophene group, a benzocarbazole group, a dibenzocarbazole group, an imidazopyridine group, an imidazopyrimidine group, an azaindole group, an azaindene group, an azabenzofuran group, an azabenzothiophene group, an azacarbazole group, an azafluorene group, an azadibenzofuran group, and an azadibenzothiophene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a di(C 1 -C 20  alkyl)phenyl group, a (C 6 -C 20  aryl)phenyl group, a di(C 6 -C 20  aryl)phenyl group, a (C 3 -C 20  heteroaryl)phenyl group, a di(C 3 -C 20  heteroaryl)phenyl group, a pyridinyl group, a (C 1 -C 20  alkyl)pyridinyl group, a di(C 1 -C 20  alkyl)pyridinyl group, a (C 6 -C 20  aryl)pyridinyl group, a di(C 6 -C 20  aryl)pyridinyl group, a (C 3 -C 20  heteroaryl)pyridinyl group, a di(C 3 -C 20  heteroaryl)pyridinyl group, a pyrimidinyl group, a (C 1 -C 20  alkyl)pyrimidinyl group, a di(C 1 -C 20  alkyl)pyrimidinyl group, a (C 6 -C 20  aryl)pyrimidinyl group, a di(C 6 -C 20  aryl)pyrimidinyl group, a (C 3 -C 20  heteroaryl)pyrimidinyl group, a di(C 3 -C 20  heteroaryl)pyrimidinyl group, a triazinyl group, a (C 1 -C 20  alkyl)triazinyl group, a di(C 1 -C 20  alkyl)triazinyl group, a (C 6 -C 20  aryl)triazinyl group, a di(C 6 -C 20  aryl)triazinyl group, a (C 3 -C 20  heteroaryl)triazinyl group, and a di(C 3 -C 20  heteroaryl)triazinyl group, 
         a11 in Formula 1B is an integer from 1 to 3, 
         E 11  in Formula 1B is selected from: 
         —F, —CFH 2 , —CF 2 H, —CF 3 , and —CN; 
         a C 1 -C 60  alkyl group or a C 1 -C 60  alkoxy group, substituted with at least one selected from —F, —CFH 2 , —CF 2 H, —CF 3 , and —CN; and 
         a substituted or unsubstituted π electron-depleted nitrogen-containing C 2 -C 60  heterocyclic group, 
         b11 in Formula 1B is an integer from 1 to 5, 
         a bond between L 11  and E 11  in Formula 1B is a carbon-carbon single bond or a carbon-fluorine single bond, 
         “*” in Formula 1B indicates a binding site to a neighboring carbon, 
         at least one substituent of the substituted π electron-depleted nitrogen-containing C 2 -C 60  heterocyclic group is selected from: 
         deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
         a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 7 -C 60  arylalkyl group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  heteroaryloxy group, a C 2 -C 60  heteroarylthio group, a C 3 -C 60  heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 11 )(Q 12 ), —Si(Q 13 )(Q 14 )(Q 15 ), —B(Q 16 )(Q 17 ), and —P(═O)(Q 18 )(Q 19 ); 
         a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 7 -C 60  arylalkyl group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  heteroaryloxy group, a C 2 -C 60  heteroarylthio group, a C 3 -C 60  heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; 
         a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 7 -C 60  arylalkyl group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  heteroaryloxy group, a C 2 -C 60  heteroarylthio group, a C 3 -C 60  heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 7 -C 60  arylalkyl group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  heteroaryloxy group, a C 2 -C 60  heteroarylthio group, a C 3 -C 60  heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 21 )(Q 22 ), —Si(Q 23 )(Q 24 )(Q 25 ), —B(Q 26 )(Q 27 ), and —P(═O)(Q 28 )(Q 29 ); and 
         —N(Q 31 )(Q 32 ), —Si(Q 33 )(Q 34 )(Q 35 ), —B(Q 36 )(Q 37 ), and —P(═O)(Q 38 )(Q 39 ); and 
         Q 11  to Q 19 , Q 21  to Q 29 , and Q 31  to Q 39  are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryl group substituted with at least one of a C 1 -C 60  alkyl group and a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 7 -C 60  arylalkyl group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  heteroaryloxy group, a C 2 -C 60  heteroarylthio group, a C 3 -C 60  heteroarylalkyl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group. 
       
     
     
         2 . The organic light-emitting device of  claim 1 , wherein
 n1 and n2 are each independently 1, 2, or 3, and   at least one of CY 1  and CY 2  in Formula 1A is a benzene group.   
     
     
         3 . The organic light-emitting device of  claim 1 , wherein
 R 1  and R 2  are each independently selected from:   hydrogen, deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a furanyl group, a thiophenyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a naphtho benzofuranyl group, a naphtho benzothiophenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, an indolofluorenyl group, an indolocarbazolyl group, an indolodibenzofuranyl group, and an indolodibenzothiophenyl group; and   a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a furanyl group, a thiophenyl group, an indolyl group, a benzofuranyl group, a benzothiophenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a naphtho benzofuranyl group, a naphtho benzothiophenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, an indolofluorenyl group, an indolocarbazolyl group, an indolodibenzofuranyl group, and an indolodibenzothiophenyl group, each substituted with at least one selected from deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a dimethylfluorenyl group, a diphenylfluorenyl group, a carbazolyl group, a phenylcarbazolyl group, a biphenylcarbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group,   b1 and b2 are each independently 0, 1, or 2, and   the sum of b1 and b2 is 0, 1, or 2.   
     
     
         4 . The organic light-emitting device of  claim 1 , wherein
 R 1  and R 2  are each independently selected from hydrogen, deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, and groups represented by Formulae 2-1 to 2-26:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 2-1 to 2-26, 
         X 21  is C(R 27 )(R 28 ), N(R 29 ), O, or S, 
         R 21  to R 29  are each independently selected from hydrogen, deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a dimethylfluorenyl group, a diphenylfluorenyl group, a carbazolyl group, a phenylcarbazolyl group, a biphenylcarbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and 
         “*” indicates a binding site to a neighboring atom. 
       
     
     
         5 . The organic light-emitting device of  claim 1 , wherein
 L 11  is selected from:   a single bond, a benzene group, a naphthalene group, a fluorene group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, and a triazine group; and   a benzene group, a naphthalene group, a fluorene group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, and a triazine group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a di(C 1 -C 20  alkyl)phenyl group, a (C 6 -C 20  aryl)phenyl group, a di(C 6 -C 20  aryl)phenyl group, a (C 3 -C 20  heteroaryl)phenyl group, a di(C 3 -C 20  heteroaryl)phenyl group, a pyridinyl group, a (C 1 -C 20  alkyl)pyridinyl group, a di(C 1 -C 20  alkyl)pyridinyl group, a (C 6 -C 20  aryl)pyridinyl group, a di(C 6 -C 20  aryl)pyridinyl group, a (C 3 -C 20  heteroaryl)pyridinyl group, a di(C 3 -C 20  heteroaryl)pyridinyl group, a pyrimidinyl group, a (C 1 -C 20  alkyl)pyrimidinyl group, a di(C 1 -C 20  alkyl)pyrimidinyl group, a (C 6 -C 20  aryl)pyrimidinyl group, a di(C 6 -C 20  aryl)pyrimidinyl group, a (C 3 -C 20  heteroaryl)pyrimidinyl group, a di(C 3 -C 20  heteroaryl)pyrimidinyl group, a triazinyl group, a (C 1 -C 20  alkyl)triazinyl group, a di(C 1 -C 20  alkyl)triazinyl group, a (C 6 -C 20  aryl)triazinyl group, a di(C 6 -C 20  aryl)triazinyl group, a (C 3 -C 20  heteroaryl)triazinyl group, and a di(C 3 -C 20  heteroaryl)triazinyl group, and   a11 is 1, 2, or 3.   
     
     
         6 . The organic light-emitting device of  claim 1 , wherein
 E 11  is selected from:   —F, —CFH 2 , —CF 2 H, —CF 3 , and —CN;   a C 1 -C 20  alkyl group substituted with at least one selected from —F, —CFH 2 , —CF 2 H, —CF 3 , and —CN; and   groups represented by Formulae 3-1 to 3-14:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 3-1 to 3-14, X 31  is N or C(R 31 ), X 32  is N or C(R 32 ), X 33  is N or C(R 33 ), X 34  is N or C(R 34 ), X 35  is N or C(R 35 ), X 36  is N or C(R 36 ), X 37  is N or C(R 37 ), X 38  is N or C(R 38 ), and X 39  is N or C(R 39 ), 
         X 41  in Formulae 3-1, 3-2, and 3-4 to 3-9 is N(R 41 ), C(R 42 )(R 43 ), O, or S, 
         at least one of X 31  to X 33  in Formulae 3-1 and 3-2 is N, at least one of X 31  to X 34  in Formula 3-3 is N, at least one of X 31  to X 35  in Formulae 3-4, 3-5, and 3-10 is N, at least one of X 31  to X 37  in Formulae 3-6 to 3-9, 3-11, and 3-12 is N, and at least one of X 31  to X 39  in Formulae 3-13 and 3-14 is N, 
         R 31  to R 39  and R 41  to R 43  are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a di(C 1 -C 20  alkyl)phenyl group, a (C 6 -C 20  aryl)phenyl group, a di(C 6 -C 20  aryl)phenyl group, a (C 3 -C 20  heteroaryl)phenyl group, a di(C 3 -C 20  heteroaryl)phenyl group, a pyridinyl group, a (C 1 -C 20  alkyl)pyridinyl group, a di(C 1 -C 20  alkyl)pyridinyl group, a (C 6 -C 20  aryl)pyridinyl group, a di(C 6 -C 20  aryl)pyridinyl group, a (C 3 -C 20  heteroaryl)pyridinyl group, a di(C 3 -C 20  heteroaryl)pyridinyl group, a pyrimidinyl group, a (C 1 -C 20  alkyl)pyrimidinyl group, a di(C 1 -C 20  alkyl)pyrimidinyl group, a (C 6 -C 20  aryl)pyrimidinyl group, a di(C 6 -C 20  aryl)pyrimidinyl group, a (C 3 -C 20  heteroaryl)pyrimidinyl group, a di(C 3 -C 20  heteroaryl)pyrimidinyl group, a triazinyl group, a (C 1 -C 20  alkyl)triazinyl group, a di(C 1 -C 20  alkyl)triazinyl group, a (C 6 -C 20  aryl)triazinyl group, a di(C 6 -C 20  aryl)triazinyl group, a (C 3 -C 20  heteroaryl)triazinyl group, and a di(C 3 -C 20  heteroaryl)triazinyl group, and 
         “*” indicates a binding site to a neighboring atom. 
       
     
     
         7 . The organic light-emitting device of  claim 1 , wherein
 E 11  is selected from:   —CN;   a C 1 -C 20  alkyl group substituted with at least one —CN; and   groups represented by Formulae 3-4(1) to 3-4(4), 3-5(1) to 3-5(4), 3-6(1), 3-7(1), 3-8(1), 3-9(1), 3-10(1) to 3-10(8), 3-11(1) to 3-11(23), and 3-12(1) to 3-12(23):   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 3-4(1) to 3-4(4), 3-5(1) to 3-5(4), 3-6(1), 3-7(1), 3-8(1), 3-9(1), 3-10(1) to 3-10(8), 3-11(1) to 3-11(23), and 3-12(1) to 3-12(23), X 41  is N(R 41 ), C(R 42 )(R 43 ), O, or S, 
         R 31  to R 37  and R 41  to R 43  are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, a di(phenyl)phenyl group, a (pyridinyl)phenyl group, a di(pyridinyl)phenyl group, a (pyrimidinyl)phenyl group, a di(pyrimidinyl)phenyl group, a (triazinyl)phenyl group, a di(triazinyl)phenyl group, a pyridinyl group, a (C 1 -C 10  alkyl)pyridinyl group, a di(C 1 -C 10  alkyl)pyridinyl group, a (phenyl)pyridinyl group, a di(phenyl)pyridinyl group, a (pyridinyl)pyridinyl group, a di(pyridinyl)pyridinyl group, a (pyrimidinyl)pyridinyl group, a di(pyrimidinyl)pyridinyl group, a (triazinyl)pyridinyl group, a di(triazinyl)pyridinyl group, a triazinyl group, a (C 1 -C 10  alkyl)triazinyl group, a di(C 1 -C 10  alkyl)triazinyl group, a (phenyl)triazinyl group, a di(phenyl)triazinyl group, a (pyridinyl)triazinyl group, a di(pyridinyl)triazinyl group, a (pyrimidinyl)triazinyl group, a di(pyrimidinyl)triazinyl group, a (triazinyl)triazinyl group, and a di(triazinyl)triazinyl group, and 
         “*” indicates a binding site to a neighboring atom. 
       
     
     
         8 . The organic light-emitting device of  claim 1 , wherein
 R 1  and R 2  are each independently selected from hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, a di(phenyl)phenyl group, a fluorenyl group, a (C 1 -C 10  alkyl)fluorenyl group, a di(C 1 -C 10  alkyl)fluorenyl group, a (phenyl)fluorenyl group, a di(phenyl)fluorenyl group, a carbazolyl group, a (C 1 -C 10  alkyl)carbazolyl group, a di(C 1 -C 10  alkyl)carbazolyl group, a (phenyl)carbazolyl group, a di(phenyl)carbazolyl group, a dibenzofuranyl group, a (C 1 -C 10  alkyl)dibenzofuranyl group, a di(C 1 -C 10  alkyl)dibenzofuranyl group, a (phenyl)dibenzofuranyl group, a di(phenyl)dibenzofuranyl group, a dibenzothiophenyl group, a (C 1 -C 10  alkyl)dibenzothiophenyl group, a di(C 1 -C 10  alkyl)dibenzothiophenyl group, a (phenyl)dibenzothiophenyl group, a di(phenyl)dibenzothiophenyl group, a indolofluorenyl group, a (C 1 -C 10  alkyl)indolofluorenyl group, a di(C 1 -C 10  alkyl)indolofluorenyl group, a (phenyl)indolofluorenyl group, a di(phenyl)indolofluorenyl group, an indolocarbazolyl group, a (C 1 -C 10  alkyl)indolocarbazolyl group, a di(C 1 -C 10  alkyl)indolocarbazolyl group, a (phenyl)indolocarbazolyl group, a di(phenyl)indolocarbazolyl group, an indolodibenzofuranyl group, a (C 1 -C 10  alkyl)indolodibenzofuranyl group, a di(C 1 -C 10  alkyl)indolodibenzofuranyl group, a (phenyl)indolodibenzofuranyl group, a di(phenyl)indolodibenzofuranyl group, an indolodibenzothiophenyl group, a (C 1 -C 10  alkyl)indolodibenzothiophenyl group, a di(C 1 -C 10  alkyl)indolodibenzothiophenyl group, a (phenyl)indolodibenzothiophenyl group, and a di(phenyl)indolodibenzothiophenyl group,   b1 and b2 are each independently 0, 1, or 2, and   the electron acceptor group is selected from —CN and groups represented by Formulae 1B-1 to 1B-30:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 1B-1 to 1B-30, 
         Z 1  to Z 3  and Z 11  to Z 13  are each independently selected from a C 1 -C 10  alkyl group and a phenyl group, and 
         “*” indicates a binding site to a neighboring atom. 
       
     
     
         9 . The organic light-emitting device of  claim 1 , wherein
 the fluorescent compound is represented by one of Formulae 10-1 to 10-6:   
       
         
           
           
               
               
           
         
         wherein, in Formulae 10-1 to 10-6, 
         D 1  to D 3  are each independently selected from electron donor groups represented by Formula 1A, and 
         A 1 , A 1a , A 1b , A 3 , and A 4  are each independently selected from electron acceptor groups represented by Formula 1B. 
       
     
     
         10 . The organic light-emitting device of  claim 1 , wherein
 the fluorescent compound is represented by one of Formulae 9-1 to 9-9:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 9-1 to 9-9, 
         CY 1 , CY 2 , R 1 , R 2 , b1, and b2 are the same as described in  claim 1 , 
         L 1  to L 3  are each independently selected from: 
         a single bond, a C 5 -C 60  carbocyclic group, and a π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group; and 
         a C 5 -C 60  carbocyclic group and a π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, each substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 5 -C 60  carbocyclic group, a (C 1 -C 10  alkyl)C 5 -C 60  carbocyclic group, a di(C 1 -C 10  alkyl)C 5 -C 60  carbocyclic group, a (phenyl)C 5 -C 60  carbocyclic group, a di(phenyl)C 5 -C 60  carbocyclic group, a (biphenyl)C 5 -C 60  carbocyclic group, a di(biphenyl)C 5 -C 60  carbocyclic group, a π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a (C 1 -C 10  alkyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a di(C 1 -C 10  alkyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a (phenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a di(phenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, a (biphenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, and a di(biphenyl) π electron-depleted nitrogen-free C 2 -C 60  heterocyclic group, 
         a1 to a3 are each independently an integer from 1 to 3, 
         R 8  to R 10  are the same as described in connection with R 1  in  claim 1 , provided that R 8  to R 10  are not hydrogen, 
         b8 to b10 are each independently an integer from 1 to 5, 
         R 1  to R 6  are the same as described in connection with R 1  in  claim 1 , 
         b1 to b6 are the same as described in connection with b1 in  claim 1 , 
         A 1  to A 6  are each independently selected from electron acceptor groups represented by Formula 1B, 
         c1 to c6 are each independently 0, 1, 2, or 3, provided that the sum of c1 and c2 in Formula 9-1 is one or more, the sum of c1 to c4 in Formulae 9-2 to 9-4 is one or more, and the sum of c1 to c6 in Formulae 9-5 to 9-9 is one or more, and 
         a bond between A 1  and CY 1 , a bond between A 2  and CY 2 , a bond between A 3  and CY 3 , a bond between A 4  and CY 4 , a bond between A 5  and CY 5 , and a bond between A 6  and CY 6  are each a carbon-carbon single bond. 
       
     
     
         11 . The organic light-emitting device of  claim 10 , wherein,
 in Formulae 9-1 to 9-9, a moiety represented by   
       
         
           
           
               
               
           
         
       
       a moiety represented by 
       
         
           
           
               
               
           
         
       
       and a moiety represented by 
       
         
           
           
               
               
           
         
       
       are each independently derived from groups represented by Formulae 8-1 to 8-7: 
       
         
           
           
               
               
           
         
         wherein, in Formulae 8-2 to 8-7, X 1  is N(R′), C(R′)(R″), O, or S, R′ and R″ are the same as described in connection with R 1  in  claim 1  and “*” indicates a binding site to a neighboring atom. 
       
     
     
         12 . The organic light-emitting device of  claim 10 , wherein
 1) in Formula 9-1, c1 is 1 or 2 and c2 is 0,   2) in Formulae 9-2 to 9-4, i) c1 is 1 or 2, c2 is 0, and the sum of c3 and c4 is 0, 1, or 2, or ii) c1 is 1, c2 is 1 or 2, and the sum of c3 and c4 is 0, 1, or 2, and   3) in Formulae 9-5 to 9-9, i) c1 is 1 or 2, c2 is 0, and the sum of c3, c4, c5, and c6 is 1 or 2, or ii) c1 is 0, c2 is 1 or 2, and the sum of c3, c4, c5, and c6 is 0, 1, or 2.   
     
     
         13 . The organic light-emitting device of  claim 1 , wherein
 the fluorescent compound is represented by one selected from Formulae 1-1 to 1-7:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 1-1 to 1-7, 
         X 51  is C(R 52 )(R 53 ), N(R 52 ), O or S, and 
         1) i) R 11  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 12  to R 20  and R 51  to R 53  is a group represented by one of Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         2) i) R 12  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11 , R 13  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         3) i) R 13  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11 , R 12 , R 14  to R 20 , and R 51  to R 53  is a group represented by Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         4) i) R 14  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11  to R 13 , R 15  to R 20 , and R 51  to R 53  is a group a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         5) i) R 15  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11  to R 14 , R 16  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         6) i) R 16  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11  to R 15 , R 17  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         7) i) R 12  is an electron acceptor group represented by Formula 1B, ii) R 11  and R 13  are each independently a group represented by one selected from Formulae 6-1 to 6-7, and iii) R 14  to R 20  and R 51  to R 53  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         8) i) R 13  is an electron acceptor group represented by Formula 1B, ii) R 12  and R 14  are each independently a group represented by one selected from Formulae 6-1 to 6-7, and iii) R 11 , R 15  to R 20 , and R 51  to R 53  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         9) i) R 12  and R 13  are each independently an electron acceptor group represented by Formula 1B, and ii) one selected from R 11 , R 14  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
         10) i) R 11  and R 12  are each independently an electron acceptor group represented by Formula 1B, and ii) one selected from R 13  to R 20  and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; or 
         11) i) R 11  is an electron acceptor group represented by Formula 1B, ii) R 12  and R 13  are each independently a group represented by one selected from Formulae 6-1 to 6-7, and iii) R 14  to R 20  and R 51  to R 53  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group: 
       
       
         
           
           
               
               
           
         
         wherein, in Formulae 6-1 to 6-7, 
         CY 4  is a benzene group, a fluorene group, a dimehylfluorene group, a diphenylfluorene group, a carbazole group, a phehylcarbazole group, a biphenylcarbazole group, a dibenzofuran group, or a dibenzothiophene group, 
         R 3 , R 4 , and R 9  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group, 
         A 3  and A 4  are each independently selected from acceptor groups represented by Formula 1B, and 
         “*” indicates a binding site to a neighboring atom. 
       
     
     
         14 . The organic light-emitting device of  claim 1 , wherein
 the fluorescent compound comprised in the emission layer is a fluorescent emitter, and   a proportion of fluorescent emission components of the fluorescent compound with respect to total emission components emitted from the emission layer is about 80% or more.   
     
     
         15 . The organic light-emitting device of  claim 14 , wherein
 the emission layer consists of the fluorescent compound; or   the emission layer comprises a fluorescent compound and further comprises a host.   
     
     
         16 . The organic light-emitting device of  claim 1 , wherein
 the emission layer comprises a host and a fluorescent dopant,   the host comprises the fluorescent compound, and   a proportion of fluorescent emission components of the fluorescent dopant with respect to total emission components emitted from the emission layer is about 80% or more.   
     
     
         17 . The organic light-emitting device of  claim 1 , wherein
 the emission layer comprises a host, an auxiliary dopant, and a fluorescent dopant,   the auxiliary dopant comprises the fluorescent compound, and   the emission layer satisfies Mathematical Expressions 1 and 2:
     E   T1(HOST)   −E   T1(AD) >0.05 electron volts  Mathematical Expression 1
 
     E   S1(FD)   −E   S1(AD) <0 electron volts,  Mathematical Expression 2
 
   wherein, in Mathematical Expression 1, E T1(HOST)  is triplet energy (expressed in electron volts) of the host, and E T1(AD)  is triplet energy (expressed in electron volts) of the auxiliary dopant,   in Mathematical Expression 2, E S1(FD)  is singlet energy (expressed in electron volts) of the fluorescent dopant, and E S1(AD)  is singlet energy (expressed in electron volts) of the auxiliary dopant, and   E T1(HOST) , E T1(AD) , E S1(FD) , and E S1(AD)  are each independently evaluated by using a Density Functional Theory (DFT) method of a Gaussian program that is structurally optimized at a level of B3LYP/6-31 G(d,p).   
     
     
         18 . A compound represented by one of Formulae 9-1 to 9-9: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 9-1 to 9-9, 
         CY 1  to CY 6  are each independently selected from a benzene group, a naphthalene group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group, 
         L 1  to L 3  are each independently selected from: 
         a single bond, a benzene group, a naphthalene group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group; and 
         a benzene group, a naphthalene group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group, each substituted with at least one selected from deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a dimethylfluorenyl group, a diphenylfluorenyl group, a carbazolyl group, a phenylcarbazolyl group, a biphenylcarbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, 
         a1 to a3 are each independently an integer from 1 to 3, 
         R 1  to R 6  and R 8  to R 10  are each independently selected from hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, a di(phenyl)phenyl group, a carbazolyl group, a (C 1 -C 10  alkyl)carbazolyl group, a di(C 1 -C 10  alkyl)carbazolyl group, a (phenyl)carbazolyl group, a di(phenyl)carbazolyl group, a fluorenyl group, a (C 1 -C 10  alkyl)fluorenyl group, a di(C 1 -C 10  alkyl)fluorenyl group, a (phenyl)fluorenyl group, a di(phenyl)fluorenyl group, a dibenzofuranyl group, a (C 1 -C 10  alkyl)dibenzofuranyl group, a di(C 1 -C 10  alkyl)dibenzofuranyl group, a (phenyl)dibenzofuranyl group, a di(phenyl)dibenzofuranyl group, a dibenzothiophenyl group, a (C 1 -C 10  alkyl)dibenzothiophenyl group, a di(C 1 -C 10  alkyl)dibenzothiophenyl group, a (phenyl)dibenzothiophenyl group, and a di(phenyl)dibenzothiophenyl group, provided that R 8  to R 10  are not hydrogen, 
         b1 to b6 are each independently 0, 1, or 2, 
         b8 to b10 are each independently 1 or 2, 
         A 1  to A 6  are each independently selected from electron acceptor groups represented by Formula 1B, 
         c1 to c6 are each independently 0, 1, 2, or 3, provided that the sum of c1 and c2 in Formula 9-1 is one or more, the sum of c1 to c4 in Formulae 9-2 to 9-4 is one or more, and the sum of c1 to c6 in Formulae 9-5 to 9-9 is one or more, and 
         a bond between A 1  and CY 1 , a bond between A 2  and CY 2 , a bond between A 3  and CY 3 , a bond between A 4  and CY 4 , a bond between A 5  and CY 5 , and a bond between A 6  and CY 6  are each a carbon-carbon single bond:
   *-(L 11 ) a11 -(E 11 ) b11 ,  Formula 1B
 
 
         wherein, in Formula 1B, 
         L 11  is selected from: 
         a single bond, a benzene group, a naphthalene group, a fluorene group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, and a triazine group; and 
         a benzene group, a naphthalene group, a fluorene group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, and a triazine group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a di(C 1 -C 20  alkyl)phenyl group, a (C 6 -C 20  aryl)phenyl group, a di(C 6 -C 20  aryl)phenyl group, a (C 3 -C 20  heteroaryl)phenyl group, a di(C 3 -C 20  heteroaryl)phenyl group, a pyridinyl group, a (C 1 -C 20  alkyl)pyridinyl group, a di(C 1 -C 20  alkyl)pyridinyl group, a (C 6 -C 20  aryl)pyridinyl group, a di(C 6 -C 20  aryl)pyridinyl group, a (C 3 -C 20  heteroaryl)pyridinyl group, a di(C 3 -C 20  heteroaryl)pyridinyl group, a pyrimidinyl group, a (C 1 -C 20  alkyl)pyrimidinyl group, a di(C 1 -C 20  alkyl)pyrimidinyl group, a (C 6 -C 20  aryl)pyrimidinyl group, a di(C 6 -C 20  aryl)pyrimidinyl group, a (C 3 -C 20  heteroaryl)pyrimidinyl group, a di(C 3 -C 20  heteroaryl)pyrimidinyl group, a triazinyl group, a (C 1 -C 20  alkyl)triazinyl group, a di(C 1 -C 20  alkyl)triazinyl group, a (C 6 -C 20  aryl)triazinyl group, a di(C 6 -C 20  aryl)triazinyl group, a (C 3 -C 20  heteroaryl)triazinyl group, and a di(C 3 -C 20  heteroaryl)triazinyl group, 
         a11 is 1 or 2, 
         E 11  is selected from: 
         —F, —CFH 2 , —CF 2 H, —CF 3 , and —CN; 
         a C 1 -C 20  alkyl group substituted with at least one selected from —F, —CFH 2 , —CF 2 H, —CF 3 , and —CN; and 
         groups represented by Formulae 3-1 to 3-14, 
         b11 is an integer from 1 to 5, 
         a bond between L 11  and E 11  in Formula 1B is a carbon-carbon single bond or a carbon-fluorine single bond, and 
         “*” in Formula 1B indicates a binding site to a neighboring carbon: 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 3-1 to 3-14, X 31  is N or C(R 31 ), X 32  is N or C(R 32 ), X 33  is N or C(R 33 ), X 34  is N or C(R 34 ), X 35  is N or C(R 35 ), X 36  is N or C(R 36 ), X 37  is N or C(R 37 ), X 38  is N or C(R 38 ), and X 39  is N or C(R 39 ), 
         X 41  in Formulae 3-1, 3-2, and 3-4 to 3-9 is N(R 41 ), C(R 42 )(R 43 ), O, or S, 
         at least one of X 31  to X 33  in Formulae 3-1 and 3-2 is N, at least one of X 31  to X 34  in Formula 3-3 is N, at least one of X 31  to X 35  in Formulae 3-4, 3-5, and 3-10 is N, at least one of X 31  to X 37  in Formulae 3-6 to 3-9, 3-11, and 3-12 is N, and at least one of X 31  to X 39  in Formulae 3-13 and 3-14 is N, 
         R 31  to R 39  and R 41  to R 43  are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a di(C 1 -C 20  alkyl)phenyl group, a (C 6 -C 20  aryl)phenyl group, a di(C 6 -C 20  aryl)phenyl group, a (C 3 -C 20  heteroaryl)phenyl group, a di(C 3 -C 20  heteroaryl)phenyl group, a pyridinyl group, a (C 1 -C 20  alkyl)pyridinyl group, a di(C 1 -C 20  alkyl)pyridinyl group, a (C 6 -C 20  aryl)pyridinyl group, a di(C 6 -C 20  aryl)pyridinyl group, a (C 3 -C 20  heteroaryl)pyridinyl group, a di(C 3 -C 20  heteroaryl)pyridinyl group, a pyrimidinyl group, a (C 1 -C 20  alkyl)pyrimidinyl group, a di(C 1 -C 20  alkyl)pyrimidinyl group, a (C 6 -C 20  aryl)pyrimidinyl group, a di(C 6 -C 20  aryl)pyrimidinyl group, a (C 3 -C 20  heteroaryl)pyrimidinyl group, a di(C 3 -C 20  heteroaryl)pyrimidinyl group, a triazinyl group, a (C 1 -C 20  alkyl)triazinyl group, a di(C 1 -C 20  alkyl)triazinyl group, a (C 6 -C 20  aryl)triazinyl group, a di(C 6 -C 20  aryl)triazinyl group, a (C 3 -C 20  heteroaryl)triazinyl group, and a di(C 3 -C 20  heteroaryl)triazinyl group, and 
         “*” indicates a binding site to a neighboring atom. 
       
     
     
         19 . The compound of  claim 18 , wherein
 the fluorescent compound is represented by one selected from Formulae 1-1 to 1-7:   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           wherein, in Formulae 1-1 to 1-7, 
           X 51  is C(R 52 )(R 53 ), N(R 52 ), O or S, and 
           1) i) R 11  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 12  to R 20  and R 51  to R 53  is a group represented by one of Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           2) i) R 12  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11 , R 13  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           3) i) R 13  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11 , R 12 , R 14  to R 20 , and R 51  to R 53  is a group represented by Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           4) i) R 14  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11  to R 13 , R 15  to R 20 , and R 51  to R 53  is a group a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           5) i) R 15  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11  to R 14 , R 16  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           6) i) R 16  is an electron acceptor group represented by Formula 1B, and ii) one selected from R 11  to R 15 , R 17  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           7) i) R 12  is an electron acceptor group represented by Formula 1B, ii) R 11  and R 13  are each independently a group represented by one selected from Formulae 6-1 to 6-7, and iii) R 14  to R 20  and R 51  to R 53  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           8) i) R 13  is an electron acceptor group represented by Formula 1B, ii) R 12  and R 14  are each independently a group represented by one selected from Formulae 6-1 to 6-7, and iii) R 11 , R 15  to R 20 , and R 51  to R 53  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           9) i) R 12  and R 13  are each independently an electron acceptor group represented by Formula 1B, and ii) one selected from R 11 , R 14  to R 20 , and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; 
           10) i) R 11  and R 12  are each independently an electron acceptor group represented by Formula 1B, and ii) one selected from R 13  to R 20  and R 51  to R 53  is a group represented by one selected from Formulae 6-1 to 6-7, and the rest are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group; or 
           11) i) R 11  is an electron acceptor group represented by Formula 1B, ii) R 12  and R 13  are each independently a group represented by one selected from Formulae 6-1 to 6-7, and iii) R 14  to R 20  and R 51  to R 53  are each independently hydrogen, deuterium, a C 1 -C 10  alkyl group, a phenyl group, a (C 1 -C 10  alkyl)phenyl group, a di(C 1 -C 10  alkyl)phenyl group, a biphenyl group, or a di(phenyl)phenyl group. 
         
       
     
     
         20 . The compound of  claim 18 , wherein
 the compound is one of Compounds 1 to 936: